DESCRIPTION: (Applicant's Abstract) Epidemiological studies of injecting drug users have revealed that the human immunodeficiency virus type 1 (HIV-1) is transmitted by shared injections. However, no rigorous virological studies have documented HIV-1 survival and transmission in the milieu of injection equipment in part due to the insensitivity of HIV-1 culture from the small volumes of blood remaining in syringes and other injection paraphernalia, and in part due to the division of scientific expertise that separates investigators from disparate disciplines. Therefore, a team of researchers including a molecular epidemiologist, a virologist, and two ethnographers has been assembled to determine HIV-1 transmission via injection equipment involving laboratory simulations of syringe use, syringe-mediated sharing, syringe disinfection, and non-syringe sharing informed by careful descriptions of actual drug injection behaviors provided by expert observers. The simulations will rely on a whole blood HIV-1 microculture assay (WBMA) that can propagate HIV-1 from microliter quantities of blood and other injectior solutions. Simulations will measure the longevity of HIV-1 infectivity in syringes, the rate at which infectivity is lost, the relative risks of sharing syringes and other paraphernalia, and the ability to disinfect syringes all under conditions encountered by drug injectors. Once these studies are completed, the information about HIV-1 survival and the likelihood of its transmission by the practices simulated can be integrated into the policy and practices of outreach programs to slow the spread of HIV-1 among drug injectors. The specific aims of this project are: 1) Develop a WBMA to detect viable HIV-1 in the small volumes of residual blood that remain in syringes. 2) Use the WBMA to quantify the duration of HIV-1 viability in syringes. 3) Use the WBMA to determine the potential for common injection practices to transmit HIV-1. 4) Use the WBMA to determine the effectiveness of bleach and other common disinfection agents. 5) Expand the WBMA to determine the risks of transmitting infectious HIV-1 from non-syringe drug injection paraphernalia such as cookers, cotton, and standing water both via laboratory simulations and in paraphernalia obtained directly from shooting galleries.